西安电子科技大学学报

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用于快速锁定全数字锁相环的反馈调节算法

谢琳琳1,2;王扬1,2;乔树山1;黑勇1   

  1. (1. 中国科学院 微电子研究所 感知中心,北京 100029;
    2. 中国科学院大学,北京 100049)
  • 收稿日期:2017-07-24 出版日期:2018-06-20 发布日期:2018-07-18
  • 通讯作者: 乔树山(1981-),男,副研究员,E-mail:qiaoshushan@ime.ac.cn
  • 作者简介:谢琳琳(1993-),女,中国科学院微电子研究所、中国科学院大学博士研究生,E-mail:xielinlin@ime.ac.cn
  • 基金资助:

    国家自然科学基金资助项目(61474135)

Feedback tuning algorithm for fast-locking all-digital phase-locked loops

XIE Linlin1,2;WANG Yang1,2;QIAO Shushan1;HEI Yong1   

  1. (1. Sensing Center, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China;
    2. Univ. of Chinese Academy of Sciences, Beijing 100049, China)
  • Received:2017-07-24 Online:2018-06-20 Published:2018-07-18

摘要:

为降低全数字锁相环的锁定时间,在分析了不同相位检测机制和滤波器结构的基础上提出了自适应的反馈调节算法.该算法将锁定过程分为粗调、一级精调、二级精调三部分,分别对应数控振荡器的三级控制码,在不同的锁定过程中使用合适的滤波器结构且可根据频率差的大小自适应调节参数.基于所提算法,在180nm CMOS工艺下实现了一款可移植的快速锁定的小数全数字锁相环.测试结果表明:平均锁定时间仅为6.4μs,相当于128个参考时钟周期(20MHz),该算法有效地缩短了锁定时间.

关键词: 频率调制, 锁相环, 全数字, 快速锁定, 反馈调节算法

Abstract:

An adaptable feedback tuning algorithm based on the analyses of various phase detection mechanisms and filter architectures is presented to shorten the locking time of all-digital phase-locked loops (ADPLLs). The algorithm divides the entire locking processes into coarse tuning, first fine tuning and second fine tuning processes corresponding to control codes of coarse, first and second fine stages in the digitally controlled oscillator (DCO). An appropriate filter architecture is chosen in each process while adaptive factors are tunable according to the value of the frequency error. A portable fast-locking fractional-N ADPLL based on the proposed algorithm is fabricated by 180nm CMOS technology. Measurement shows that the average locking time is only 6.4μs, that is, 128 reference cycles with a 20MHz clock. The locking time is reduced by the algorithm effectively.

Key words: frequency modulation, phase locked loop, all digital, fast locking, feedback tuning algorithm